Known flushing devices for a vacuum toilet having a urinal may necessitate triggering a flushing action, after use of the urinal, by activating a triggering device. This then may result in flushing liquid being supplied to the urinal, and subsequently in a suction valve being opened in order to lead impurities contained in a discharge line of the urinal, as well as the flushing liquid, into the region of a wastewater tank. In this arrangement the transport process may usually be effected by a pressure differential between the wastewater tank and the space where the vacuum toilet is located. In conventional systems for flushing a vacuum toilet, during the flushing procedure there may be very considerably noise emission because of the airflows caused during the flushing procedure, which noise emission may be further amplified by a funnel effect of the urinal bowl or the toilet bowl. This problem was, for example, addressed in DE 10 2006 016 030 A1. For this purpose noise reduction of a vacuum toilet unit was realized by the supply of secondary air.